Radiation Monitoring Devices, Inc. proposes to design and build a portable bacteria sensor to identify Francisella tularensis, a CDC Category A agent of bioterrorism, in the field. The instrument will consist of a disposable microfluidic platform for carrying out the fluorescence labeling and immunocapture steps and a fluorescence detector utilizing our single-photon sensitive Geiger-mode micro avalanche photodiodes (muAPDs). muAPDs are rugged and can be battery-powered due to their low power requirements. The addition of appropriate collectors would permit detection and identification of bacteria in the air, soil, water and clinical material. The proposed Phase I studies include exploratory and optimization experiments in three areas: (1) fluorescent labeling of F. tularensis by non-specific DNA dyes or, if necessary, by fluorescent antibody; (2) selective immunocapture of the labeled bacteria by monoclonal antibody-coated magnetic beads; and (3) construction of a detector and analysis of the fluid flow of the labelled bacteria through poly(dimethylsiloxane) microchannels. Phase II studies will include development and testing of prototype microfluidic devices, final design of the muAPD detection system, integration of the microfluidics platform with the detector, and evaluation of the ability of the integrated prototype instrument to detect and identify F. tularensis.